Towards the end of last century, Mr. de Winton called attention to what was considered to be a new British mouse--the Yellow-necked Mouse (_Apodemus flavicollis_), distinguished from the Wood Mouse by its larger size, the head and body measuring four and a quarter inches, and the brown spot on the chest commonly found in the Wood Mouse developed into an orange cross whose arms are connected with the upper side coloration--described as golden brown. This is a feature that at once attracts attention where this form occurs; but there is another distinction out of sight--there being three additional bony joints in the tail, that is thirty instead of the twenty-seven in the tail of an ordinary Wood Mouse. Whether it is a really distinct species or the typical form of the Wood Mouse is at present open to question. It is found chiefly in the southern and eastern portions of England, but its distribution also includes Northamptonshire, Herefordshire, and Northumberland. Other local races have been distinguished also as distinct species or sub-species under the name of Hebridean Field Mouse (_A. hebridensis_) with the white of the under parts tinted with buff; Fair Isle Field Mouse (_A. fridariensis_), like the Yellow-necked but without the collar; St. Kilda Field Mouse (_A. hirtensis_) with brown under parts; and Bute Field Mouse (_A. butei_), darker, with shorter tail and ears. *House Mouse* (_Mus musculus_, Linn.). The most familiar, the most widely distributed and most numerous of the mammals of our country, the Common or House Mouse, stands in little need of nice description. Although of a timid and retiring nature, it can on occasion exhibit not only bold familiarity, but actual friendliness to mankind to which it has been attached for ages, preferring to live in palace or hovel with human beings to the open-air life of woods and fields. Not that he is not to be found in the open air; but then it is mostly in the immediate neighbourhood of a house, where he can make his runs in ricks of corn--mountains of food. It is this easy method of despoiling man of his goods that caused the Mouse in ancient days to attach himself to the huge creature that is so impotent in ridding himself of small adversaries. The domestic Mouse is considered to have had its home, its place of origin, in Asia, whence it has spread to every part of the world where man has gone. In most cases, it may be presumed with safety, it has travelled cosily stowed away in his stores and merchandise, so that as soon as the human migrant has built himself a home he finds that the Mouse is in occupation, and demanding a share of his food. In spite of all his serious depredations, our literature teems with evidence that the victim has always retained some kindly feeling for his pretty four-footed oppressor.